i recently attended a seminar on a completely different subject, early on they had all the attendee's take part in an excercise, it helped us all understand the subject & problems being discussed, It helped clarify the issue and the excercise will stick in my mind for a long time.

i read a transgender story once that used an example of having ones shoes on the wrong feet, they can still walk and do most things, but their brain will be screaming(niggling?), it's not right, and there's only one way to fix it.

if you can find the story, maybe ask them to switch their shoes for the duration of your talk, and that may help them realise that while they were troubled for a short time, that niggling /screaming sense in your mind of "i'm not right" that TG's have, must be endured until it can be sorted.

someone on BigCloset might be able to point you to the story, it was a very long time ago i read it.

a second example came to mind, left handed people used to be persecuted as demonic, one of my own sisters only 50 years ago at a catholic primary school was punished (caned) every time the nuns saw her writing with her left hand. i'm sure you'll have some lefties in your congregation, different is not wrong/demonic, how people treat those that are different can be both wrong and demonic.

if you have a multiracial congregation, well maybe not go there, it can be a explosive subject.

just some ideas, good luck hope all goes well.